Figure 1

Example of an CM: SF-36 item pair plot (for `Vigorous activities’) lying far from a selection of remaining item pair plots. a Item pair plots for `Vigorous activities’ and `Walking 150 metres’. b Item pair plots for `Vigorous activities’ and `Bathing or dressing yourself’. c Item pair plots for `Vigorous activities’ and `Climbing one flight of stairs’. d Item pair plots for `Vigorous activities’ and `Lifting or carrying groceries’.